There is an English saying:“36”Until recently, few people took the saying seriously.
Now, however, doctors have begun to look into laughter and the effects it has on the human body.37
Tests were carried out to study the effects of laughter on the body. People watched funny films while doctors checked their hearts, blood pressure, breathing and muscles. It was found thatlaughter has similar effects to physical exercise.38. If laughter exercises the body, it must bebeneficial.
Other tests have shown that laughter appears to be able to reduce the effect of pain on the body. In one experiment doctors produced pain in groups of students who listened to different radio programs. The group that tolerated the pain for the longest time was the group listening to a funny program.39.
40. They have found that even if their patients do not really feel like laughing, makingthem smile is enough to produce beneficial effects similar to those caused by laughter.

A．Laughter can extend one’s life.

B．As a result of these discoveries, some doctors in the United States now hold laughter clinics to help their patients.

C．The reason is that it helps to produce a kind of chemicals in the brain which diminish both stress and pain.

D．It increases blood pressure, the heart beating and breathing; it also works several groups of muscles in the face, the stomach and even the feet.

E. Although laughter helps cure the disease, doctors still can not put this theory into clinic practice.
F. Laughter is the best medicine.
G. They have found that laughter really can improve people’s health.